Under/Over Watering? Lack of Nutrients? Too much PPFD?

if you deviated from this, you are watering wrong: 1 - water entire volume of substrate, no dry pockets. If soiless, get 10% runoff. 2 - wait for top layer to dry and repeat. high water capacity wait for about 1" deep to dry. if coco, when it starts to turn color is fine. This is a healthy wet-dry cycle for a plant. you can push this a bit more in flower, if you want to. One thing -- looks like a small plant in a big pot. Until it is a proper size you follow those 2 simple steps for a diameter around the plant -- make sure it gets wet all the way to the bottom and if soilless, get 10% runoff. In future, use an appropriately sized pot to plant size and pot up as necessary. There is no reason not to do this. Potting up does not cause "shock" as some would lead you to believe. Yet to see 1 shocked plant from a potting up in 6 years and hundreds of transplants... bro-science nonsense. Your vpd matters. If sky-high, it could cause this droop. if the substrate incredibly dry, that's a good chance it is the cause too. did you increase light strenght lately or get it closer? if not it looks fine based on internode length (stem between two nodes). If this gets too tight or too lanky, that's your guide to adjusting light intensity. you'll see new nodes very tight before it causes this sort of reaction.